1. Field of the Invention
This invention relates to a sealing device for sealing two members which are relatively rotating, and more particularly to a sealing device which is unitized.
2. Description of the Related Art
One sealing device 100 such as shown in FIG. 9 is conventionally available. The sealing device 100 comprises a seal member 101 to be mounted onto a housing 104 and a sleeve member 102 to be mounted onto a shaft. The seal member 101 is provided with a metal ring 103 made up of a cylindrical portion 101a and an inwardly directed flange 101b. This metal ring 103 is provided with baked and molded rubber-like elastic members on both sides of the peripheral thereof, and has a rubber portion 105 which is fitted into the inner peripheral of the housing 104.
From the inwardly directed flange portion 101b, a seal lip 106 is extended such that the seal lip 106 slidably contacts the outer peripheral of the sleeve member 102 to seal a sealing liquid.
The seal lip 106 is provided with a dust lip 107 on the atmosphere side thereof to prevent entry of dust in the atmosphere into the device.
The inwardly directed flange 101b is further provided with a seal end projection 108 which is in contact with the sleeve member 102 to bring the inwardly directed flange 101b into contact with the sleeve member 102.
The inner peripheral of the sleeve member 102 is provided with a fitted portion 109 made of a rubber-like elastic member which is in contact with the shaft.
A second example of the conventional sealing device will be shown in FIG. 10. This sealing device 110 also comprises a seal member 111 and a sleeve member 112. The seal member 111 is provided with a seal lip 113, a dust lip 114, and a seal end portion 116 which is in contact with an end surface of the sleeve member 112. Reference numeral 115 designates a bend portion formed by bending the end portion of the sleeve member 112.
Further, a third example of the conventional sealing device will be shown in FIG. 11. This sealing device 120 consists of four (4) components. That is, the device 120 comprises an outer ring 121, and an inner ring 122, and the assembly of a seal member 124 and a sleeve member 123 is contained within the outer ring 121 and the inner ring 122.
As shown in FIG. 12 as a fourth example, an integrated type sealing device is known, in which a protection ring 133 is fitted into the outer peripheral of a seal member 134 and covers the opening formed between the seal member 134 and a sleeve member 132 (U.S. Pat. No. 4,448,426).
However, in the first example of the conventional sealing device 100, the seal member 101 and the sleeve member 102 are not integrated and thus are mutually separable. When the bearing plays, or the shaft moves in the direction of the arrow in FIG. 9 during its repair or overhaul causing a clearance to be formed between the projection 108 of the seal end surface and the sleeve member 102. The device as a result easily admits dust and sludge into an internal space. This causes the dust lip 107 and the seal lip 106 to be worn in a short period of time, thereby impairing the durability of the device.
The opening provided between an end surface 130 on the atmosphere side of the seal member and the sleeve member 102 allows external dust, sludge or the like to directly reach the projection 108. This causes not only the sliding portion to be worn in a short period of time but also a clearance to be formed, thereby allowing further entry. Moreover, the detachable construction of the device may additionally require careful handling so as not to damage the lip portion of the seal lip 106.
In the second example of the conventional sealing device 110, which is the example of a unitized device consisting of two components, the assembling operation requires the insertion of the sleeve member 112 into the seal member 111 and bending of an end portion 115 of the sleeve member 112. Accordingly, the problems exist in the bending operation of the end portion 115 of the sleeve member 112 which is an additional process in assembling and in the construction which is subject to entry of dust as is the case with the first sealing device 100.
In the third example of the conventional sealing device 120, the number of components reaches as many as four (4), thereby not only complicating the assembling process but also increasing the cost.
In the fourth example of the sealing device which is of the integral structure and in which the opening is covered, the protection ring 133 is fixed. This not only causes the shaft to be either eccentrically rotated or eccentrically mounted during mounting operation but also causes the protection ring 133 to interfere with the rotating sleeve member 132 with an axially applied thrust. As a result, the rubber material deteriorates due to exposure to excessive heat and its life is significantly reduced.
To avoid such problems, a large clearance is given between the two members 133, 132. This large clearance, however, impairs the sealing performance against dust and sludge entering from outside.